Good question. I can't answer it though. It's one only you can answer. I failed to do the work at \~16, so therapy didn't help me at that age. I showed up to therapy weekly but didn't practice daily. Same therapy \~10 years later was transformative. The difference was me. I put in the work. I practiced daily. And it's not even that much time. 15 minutes or so, twice a day. Later on in the process I used to do it in the car on the way to and from work. Someone else here said they practiced two hours a day and were able to achieve fluency in a matter of a couple of months. *I'd advise against measuring your success against anyone else.* My point is that the more work you put into practice, the greater your potential for success. If you're serious about becoming fluent, and you're ready to dedicate the time and effort, YES! 19 is a good age to start. 19, 9, or 49... IDK that age is all that important. It's about committing to doing the work.